Case 19.2
ENVIRONMENTAL PROTECTION AGENCY V. EME HOMER CITY GENERATION, L.P.
Supreme Court of the United States
134 S. Ct. 1584; 188 L. Ed. 2d 775; 2014 U.S. LEXIS 3108 [April 29, 2014]
FACTS:
Congress and the Environmental Protection Agency (EPA or Agency) have, over the course of
several decades, made many efforts to deal with the complex challenge of curtailing air pollution
emitted in upwind States, but causing harm in other, downwind States.
The Clean Air Act (CAA or Act) directs the EPA to establish national ambient air quality standards
(NAAQS) for pollutants at levels that will protect public health.
Once EPA settles on a NAAQS, the Agency must designate “nonattainment” areas (locations where
the concentration of a regulated pollutant exceeds the NAAQS).
Each State must submit a State Implementation Plan (SIP) to the EPA within three years of any new
or revised NAAQS.
From that date, if the EPA determines that a State SIP is inadequate, the Agency has two years to
promulgate a Federal Implementation Plan (FIP).
Among other components, the CAA mandates SIP compliance with the Good Neighbor Provision,
which requires SIPs to “contain adequate provisions…prohibiting…any source or other type of
emissions activity within the State from emitting any air pollutant in amounts which
will…contribute significantly to nonattainment in, or interfere with maintenance by, and other
State with respect to any…NAAQS.”
Several times over the past two decades, the EPA has attempted to delineate the Good Neighbor
Provision’s scope by identifying when upwind States “contribute significantly” to nonattainment
downwind.
The D.C. Circuit Court found fault with the Agency’s 2005 attempt, the Clean Air interstate Rule, or
CAIR, which regulated both nitrogen oxide (NOX) and sulfur dioxide (SO2) emissions in 27 upwind
States to achieve downwind attainment of three NAAQS.
A group of state and local governments (State respondents), joined by industry and labor groups
(Industry respondents), sought a review of the EPA’s Cross-State Air Pollution Rule (known as the
Transport Rule).
PROCEDURE: The U.S. Court of Appeals for the D.C. Circuit vacated the Transport rule in its entirety.
ISSUE: Does the EPA appropriately allocate among multiple contributing upwind States responsibility
for a downwind State’s excess pollution?
RULE: “Under the Transport Rule, an upwind State ‘contributed significantly’ to downwind
nonattainment to the extent its exported pollution both (1) produced one percent or more of a NAAQS
in at least one downwind State and (2) could be eliminated cost-effectively, as determined by EPA.
Upwind States would be obliged to eliminate all and only emissions meeting both of these criteria.”
REASONING:
1. The EPA’s task is to reduce upwind pollution, but only in “amounts” that push a downwind State’s
pollution concentration above the relevant NAAQS.
2. To identify which emissions were to be eliminated, EPA considered both the magnitude of upwind
already invested.
ADDITIONAL INFORMATION:
Upwind pollutants that find their way downwind are not left unaltered by the journey. Rather, as
the gases emitted by upwind polluters are carried downwind, they are transformed, through
various chemical processes, into altogether different pollutants. The offending gases at issue in
these cases—nitrogen oxide (NOX) and sulfur dioxide (SO2) often develop into ozone and fine
particulate matter (PM2.5) by the time they reach the atmospheres of downwind States.
The EPA’s chore is to quantify the amount of upwind (NOX and SO2) that must be reduced to